1. Field of the Invention
The present invention relates to a tactile reading device using a bimorph piezo-electric actuating element as an actuating source.
2. Description of the Related Art
As disclosed in, e.g., Jpn. UM Appln. KOKAI Publication No. 62-164380, in a conventional braille type cell, a plurality of bimorph piezo-electric actuating elements corresponding to a number of sensing rods constituting a braille type unit of display are provided in the horizontal direction in a required number of steps, with the sensing rods being mounted on the free end portions of the piezo-electric actuating elements. When a required piezo-electric actuating element is selectively driven, the corresponding sensing rod is vertically moved by the vertical displacement of the free end portion of this piezo-electric actuating element, so that the distal end portion of the sensing rod projects from a finger touch scanning portion, thereby displaying braille type information.
In this conventional tactile reading device, since the piezo-electric actuating elements are arranged in the horizontal direction, a large horizontal space is required. In addition, since the sensing rods move in the vertical direction, the space must also be large in the vertical direction, making it difficult to downsize a braille type cell module constituted by necessary constituent elements including the piezo-electric actuating elements and the sensing rods. In order to display character information occupying a large number of lines or graphic information, sensing rods must be provided at a high density on a necessary sensing surface. However, in the conventional tactile reading device in which the piezo-electric actuating elements are arranged in the horizontal direction, it is difficult to display such information due to structural problems.
In order to solve these problems, there is provided a braille type cell in which piezo-electric actuating elements are arranged in the vertical direction, sensing rods which are driven in the vertical direction are provided above the piezo-electric actuating elements, the sensing rods being driven through a means for converting the horizontal movement of the free end portions of the piezo-electric actuating elements to a vertical movement. As a result, character information occupying a large number of lines and graphic information, to a certain degree, can be displayed.
However, a strong demand has arisen for further down-sizing of a braille type system and for fine graphic information display.